511
FXUS65 KBYZ 121929
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
129 PM MDT FRI JUN 12 2026
KEY MESSAGES
- COLD FRONT THIS EVENING USHERS IN COOLER CONDITIONS AND SHOWER
CHANCES INTO SATURDAY. A FEW THUNDERSTORMS ARE POSSIBLE THIS
AFTERNOON AND EVENING OVER NORTHERN AREAS.
- LIGHT SNOW ACCUMULATIONS ARE EXPECTED IN THE MOUNTAINS TONIGHT
INTO SATURDAY WITH IMPACTS TO RECREATION AND TRAVEL, INCLUDING
THE BEARTOOTH HWY.
- WARMING AND MOSTLY DRY CONDITIONS SUNDAY INTO TUESDAY.
DISCUSSION
THROUGH THURSDAY...
A SHORTWAVE AND COLD FRONT, ASSOCIATED WITH A PARENT AREA OF LOW
PRESSURE CENTERED OVER FAR NW ONTARIO WILL DROP INTO THE REGION
STARTING LATE THIS AFTERNOON. THIS WILL USHER IN COOLER
CONDITIONS, NORTH TO NORTHEAST WINDS, AND INCREASING SHOWER
CHANCES AS A BAND OF FRONTOGENESIS DROPS SOUTH INTO THE SOUTHERN
MOUNTAINS AND FOOTHILLS. A FEW THUNDERSTORMS ARE POSSIBLE OVER
NORTHERN AREAS THIS AFTERNOON AND EVENING, AND CAMS DO SHOW A
COUPLE HELICITY TRACKS, THOUGH FOR THE MOST PART, WEAK
THUNDERSTORMS ARE ANTICIPATED. ALONG WITH THE BAND OF
FRONTOGENESIS, NORTHEASTERLY UPSLOPE FLOW WILL DEVELOP, FAVORING
THE NORTHERN ASPECTS OF THE SOUTHERN MOUNTAINS AND FOOTHILLS. LOOK
FOR SHOWERS TO INCREASE IN COVERAGE TONIGHT INTO EARLY SATURDAY,
ESPECIALLY OVER THE SOUTH. SHOWERS DECREASE IN COVERAGE BY
SATURDAY AFTERNOON, THOUGH WITH CYCLONIC FLOW IN PLACE, ISOLATED
SHOWERS WILL LINGER OVER PORTIONS OF THE AREA TO THE EVENING. WEAK
INSTABILITY OVER THE REGION MAY ALLOW FOR A FEW RUMBLES. PRECIPITATION
TOTALS LOOK TO RANGE FROM A FEW HUNDREDTHS TO A TRACE OVER THE
NORTH, TO BETWEEN 0.50 TO 1 INCHES OF PRECIPITATION, WITH LOCALLY
HIGHER TOTALS OVER THE NORTHERLY UPSLOPE REGIONS OF THE SOUTHERN
MOUNTAINS/FOOTHILLS. THERE IS A MODERATE TO HIGH CHANCE OF AT
LEAST 0.25 INCHES OF PRECIPITATION SOUTH AND WEST OF A MELVILLE TO
BILLINGS TO ALZADA LINE. SNOW LEVELS LOOK TO FALL AS LOW AS 7,500
FEET SATURDAY MORNING, WITH SOME LIGHT SNOW ACCUMULATIONS
EXPECTED IN THE SOUTHERN MOUNTAINS. GREATEST TOTALS WILL BE FOUND
ON NORTHERLY ASPECTS ABOVE 9,000 FEET. SNOW WILL LIKELY IMPACT THE
BEARTOOTH HIGHWAY, AND HAVE ISSUED A WINTER WEATHER ADVISORY, IN
EFFECT FROM THIS EVENING THROUGH SATURDAY MORNING. PREPARE FOR
IMPACTS TO RECREATION AND TRAVEL IN THE HIGH COUNTRY.
ENSEMBLES GENERALLY DEPICT DRIER NORTHWEST FLOW WITH OCCASIONAL
PIECES OF ENERGY BRINGING ISOLATED SHOWER AND WEAK THUNDERSTORM
ACTIVITY TO THE REGION IN THE AFTERNOONS/EVENINGS SUNDAY INTO
TUESDAY. THE THREAT FOR STRONG TO SEVERE THUNDERSTORMS DURING THIS
TIMEFRAME IS VERY LOW. BY LATE TUESDAY INTO WEDNESDAY, A MORE
ACTIVE WAVE IS POSSIBLE WITH ENSEMBLES DEPICTING ENERGY MOVING THE
REGION IN NORTHWEST FLOW. TEMPERATURES ARE FORECAST TO RANGE
FROM THE 50S AND 60S SATURDAY, TO THE 60S TO LOWER 70S SUNDAY.
TEMPERATURES THEN WARM INTO THE 70S TO LOWER 80S MONDAY THROUGH
THURSDAY, THOUGH TUESDAY COULD SEE TEMPERATURES CLIMB INTO THE
MIDDLE 80S. STP
AVIATION
18Z DISCUSSION...
ISOLATED TS ARE POSSIBLE ACROSS EAST-CENTERAL MT THIS EVENING
INCLUDING AT KMLS/KBHK. IMPACTS TO ANY TERMINAL ARE LOW (30%
CHANCE). AFTER 00Z AN AREA OF RAIN SHOWERS AND MVFR CIGS MOVES
INTO THE REGION WITH THE HIGHEST IMPACTS NEAR THE MOUNTAINS. MVFR
CONDITIONS WILL LAST FROM ROUGHLY 00Z THROUGH 15Z AT KBIL AND MAY
LINGER THROUGH THE ENTIRE PERIOD AT SITES NEAR THE MOUNTAIN
(KSHR/KLVM). KBIL/KSHR/LVM MAY SEE IFR CIGS AND VIS DURING THE
SHOWERS, HOWEVER CONFIDENCE IS LOW AND THUS I KEPT THE TAFS AT
MVFR. MOUNTAINS WILL BE FULLY OBSCURED STARTING AROUND 00Z. WIND
THROUGH THE PERIOD WILL FLUCTUATE BETWEEN NW AND NE WITH GUSTS UP
TO 25 KTS POSSIBLE. KLVM WILL FLIP TO AN EAST WIND AFTER 02Z. WMR
PRELIMINARY POINT TEMP/POPS
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 049/064 043/070 047/080 055/087 058/076 050/079 051/082
94/W 00/U 00/U 00/N 12/T 11/U 11/B
LVM 041/060 034/068 041/077 048/085 050/076 043/078 044/080
97/T 10/U 00/U 00/N 11/N 11/U 11/B
HDN 047/064 039/070 041/079 051/086 055/074 046/078 049/082
95/W 00/U 00/U 00/N 23/T 11/U 11/B
MLS 048/064 043/072 047/076 051/081 055/072 048/075 050/080
21/B 00/U 00/U 01/E 43/T 11/U 11/B
4BQ 048/061 041/068 045/074 050/081 055/072 048/076 050/081
98/W 00/U 00/U 01/B 33/T 11/U 11/B
BHK 043/061 038/071 043/073 046/076 050/069 044/072 045/078
21/N 00/U 01/N 12/T 44/T 12/W 11/B
SHR 042/058 036/065 038/075 046/081 050/072 043/075 045/079
++/T 11/U 00/N 00/B 12/T 11/U 11/B
BYZ WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY IN EFFECT FROM 6 PM THIS EVENING TO
NOON MDT SATURDAY FOR ZONE 67.
WY...NONE.
WEATHER.GOV/BILLINGS
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